Polymers vary widely in their resistance to burning. Some, such as the polyolefins, polystyrene, polyalkyl acrylates and methacrylates, and the like, burn readily. Polytetrafluoroethylene, polyvinylidene chloride and polyvinyl chloride, on the other hand, have a rather high resistance to burning. In any event, it obviously is highly desirable that, for certain applications, a polymer should have a high degree of flame retardance so that it will meet the requirements of various building codes or that it will meet safety standards imposed on toys, carpeting, drapery materials, automotive applications, etc.
The treatment of these more flammable polymers to increase their resistance to burning is well known; such treatment generally has involved the incorporation in the polymer composition of substantial proportions of antimony oxide, halogenated paraffins, halogenated hydrocarbons and low molecular weight phosphate esters. Ordinarily, though, the effective use of these and other additives has required their presence in such high concentrations as to adversely affect the desirable properties of the polymer. Thus, such desirable properties as hardness, clarity, strength, elasticity, etc., are diminished significantly by the presence of large amounts of a flame-retardant chemical.
The formulator's goal, in preparing a flame-retardant polymer composition, is to add just enough of the flame retardant compound so as to provide the desired degree of flame retardance, but no more than this minimum amount, so as to the polymer. Frequently, it is not possible to select a flame-retardant which will meet these requirements satisfactorily.
The formation of ammonium salts of phosphoric acid resulting from the reaction of CH.sub.3 CH(OH)CH.sub.2 OH and (CH.sub.2 CHOH).sub.2 with phosphorus oxychloride is shown in "Organic Phosphates," Ukita et al., Pharm. Bull (Tokyo) 5, 121-6 (1957). The salts are said to be insoluble in isopropyl alcohol. They were prepared for purposes of comparison with cyclic nucleotides. There is no suggestion of their utility as flame-retardants.
The preparation of the calcium salt of pentaerythritoldiiodohydrin phosphoric acid is shown in "Iodine-Containing Aliphatic Phosphoric Acid Esters," Eidebenz et al., Arch. Pharm. 280, 227-31 (1942).
The ammonium salt of 5,5-dimethyl-2-hydroxy-2-oxo-1,3,2-dioxaphosphorinane is shown in "Cyclic Organophosphorus Compounds-III," Edmundson, Tetrahedron, 21(9), 2379-87 (1965). Also, the preparation of the potassium salt is shown by neutralization of the acid with aqueous potassium bicarbonate and evaporation to dryness.